COMPOSITE OXIDE MATERIAL AND EXHAUST GAS PURIFICATION CATALYST USING SAME

摘要

The present invention addresses the problem of providing an oxygen storage material for an exhaust gas purification catalyst, said oxygen storage material exhibiting more excellent stability even under high-temperature conditions. The present invention provides a composite oxide material characterized by comprising: ceria-zirconia composite oxide crystalline particles having pyrochlore structure; and lanthana-zirconia composite oxide crystals which have pyrochlore structure and which are present on the surface of the crystalline particles. At least some of the lanthana-zirconia composite oxide crystals form a solid solution with the ceria-zirconia composite oxide crystalline particles on the surface thereof. In the composite oxide material, the pyrochlore structure of the ceria-zirconia composite oxide is stabilized, so that the composite oxide material is protected against oxygen storage capacity deterioration associated with a phase change into fluorite structure.